In the year 2148, explorers on Mars discovered the remains of an ancient spacefaring civilization.In the decades that followed, these mysterious artifacts revealed startling new technologies, enabling travel to the furthest stars.The basis for this incredible technology was a force that controlled the very fabric of space and time.They called it the greatest discovery in human history.The civilizations of the galaxy call it...MASS EFFECT

The series makes heavy use of a large number of science fiction tropes. Nearly every aspect of the setting is well thought-out, with hefty amounts of technical, cultural, and historical background data provided by an Encyclopedia Exposita. It's a Reconstruction of the Space Opera.

The games' protagonist is Commander Shepard, who, in true Bioware fashion, is customizable right down to their sex. A distinguished military officer, Shepard is selected to become the first human Spectre, an elite group of galactic peacekeepers given carte blanche to go about their job as they see fit. Unfortunately, nothing about the review process goes as planned, and Shepard is soon thrust into a life-or-death struggle with Saren Arterius, a former Spectre, who plans to seize control of the galactic capital with the help of an immense warship named Sovereign and an army of robotic Geth. Nothing is as it seems, however, and soon the very survival of organic life is at stake due to the shadowy threat of the legendary Reapers.

The classes presented to you are divided up between three affinities: Combat, Tech and Biotic. Combat classes have abilities based on amplifying their weapons and own reflexes to make them more vicious in combat. Tech classes counter the opponents' technology (jamming their weapons, overloading their shields, sending out attack drones) and hacking Mecha Mooks to attack their own. Biotic classes project the eponymous Mass Effect with their own bodies, giving them Mind Over Matter powers that are based on warping space and gravity and providing biotic barriers. Shepard can choose one of three specialized classes for maximum effectiveness in one style, or one of the three hybrid classes, sacrificing the full range of options and abilities of either class type for maximum flexibility. Your own team tends to be an eclectic mix of all three and you are only allowed to take two members with you on any given mission, so choosing which ones would be helpful for the circumstances is vital. These classes are broken down as such:

Adept: Full Biotic, based on manipulating gravity and controlling crowd flow via a type of Full-Contact Magic

Soldier: Full Combat, powers are focused on dealing as much raw damage through the use of weapons and grenades

Engineer: Full Tech, very useful in stripping away enemy defenses and distracting the enemy via automated turrets and drones

Sentinel: Tech/Biotic, mixes the defensive strategies Tech offers with the damaging power of Biotics

Infiltrator: Tech/Combat, uses Tech based abilities to offer enhanced damage bonuses in a Combat based style

Vanguard: Biotic/Combat, enhances physical abilities with Biotics while using Combat to deal more damage at close range

Like previous BioWare games, Mass Effect employs a Karma Meter with two moral endpoints. Essentially, the meter measures the player's place on the Sliding Scale of Idealism Versus Cynicism; Paragon choices move toward Idealism and Renegade choices toward Cynicism. Most responses tend to be either nice or mean ways of saying the same thing ("I'm sorry, but please tell me what happened" versus "Get over it and tell me what happened"), but as you climb each meter, you unlock new conversation options which can take things in a completely different direction ("I'm an Action Survivor too, let's bond"; "Get a Hold of Yourself, Man!! Quit Your Whining!"). The Railroading on dialogue choices may not allow complete freedom of choice but it helps hold the plot together: whether you choose to play Shepard nice or mean, s/he is still a hero either way.

The Paragon is the more humane, compassionate, diplomatic end of the spectrum, one who tries to solve problems and disputes as peacefully as possible, or at least with the motive of protecting the innocent, but shows little if any pity towards corruption or immoral actions. Paragon dialogue also tends to take a more cooperative, egalitarian stance to the other sentient species of the galaxy and the Citadel Council. Succinctly, this path is The Fettered.

The Renegade is a more ruthless hero who believes in solving problems and disputes by force, intimidation, and an "I Did What I Had to Do" philosophy, preferring to kill the enemy at all costs and allowing petty immoral acts to slip by to achieve the bigger goal. Renegade conversation options tend to show little regard for the council and more of a "humans first" position. To put it simply, this path is The Unfettered.

These choices are omnipresent, as every conversation in the game is interactive and most give a chance to score Paragon and Renegade points. Yes, Paragon and Renegade: you can climb both sides of the scale simultaneously. Instead of each choice pulling you in one direction or another, there are separate meters for Paragon and Renegade, and choosing towards one does not change your position on the other. This allows much more complex characterization; there's no reason you can't play (say) a moral xenophobe who is Paragon towards humans but Renegade towards aliens, a True Neutral character who adapts to fit each situation, or even alternate every time you're given a choice. Of course, there are benefits to committing to either end; in every game but the last, there are dialogue options and even missions you can't access at all unless you have a high Paragon/Renegade score. (The third unlocks options based on your total Karma Points, and adds non-flavored "Reputation" points as well.) And in terms of replay value, it's kind of brilliant, since no matter what path you choose, there's always at least one other branch (sometimes more) you consciously turned away from.

And these link up with the other theme of the franchise: Continuity Porn, the Butterfly of Doom and the Old Save Bonus. There are plenty of NPCs you can choose to kill, but if you don't, they will almost certainly appear in the next game. (Where, possibly, they can be killed a second time.) Mass Effect has hundreds of named characters, and the list of ones who don't re-appear in the next game is a lot shorter than the list of those who do; this creates a sense of not only a living, breathing universe, but the feeling that you, Commander Shepard, have some significance within it. And these are just the casual choices—what about the ones where you decide the fates of entire sentient species? Players of the franchise are known to run two or more saved games, playing and re-playing to see how their choices impact the galaxy.

The series also contains several comics: Mass Effect: Redemption, Mass Effect: Evolution, and Mass Effect: Invasion are graphic novels that consist of four issues each, while Mass Effect: Incursion, Mass Effect: Inquisition, and Mass Effect: Conviction are short 8 page stories. A fourth multiple issue comic, Mass Effect: Homeworlds is due to begin in April 2012, with each issue focusing on a main character of Mass Effect 3.

There are also two IOS games, titled Mass Effect: Galaxy and Mass Effect Infiltrator, respectively, as well as Mass Effect: Datapad, a companion app for Mass Effect 3. A movie and an anime have also been officially announced. The fandom is unsure how to take this.